The invention pertains to transducers utilizing piezoelectric elements for producing vibrations.
Transducers used in marine applications for producing underwater sound vibrations such as used in submarine detection, underwater survey, sound detection and locating, and the like, often use piezoelectric elements energized by electrical energy for mechanically vibrating a diaphragm or shell to produce the desired vibrations. One common piezoelectric transducer consists of a stack of piezoelectric ceramic disks or bars wired in parallel to produce longitudinal vibration in contact with a metallic shell. As the shell lengthens and contracts due to stresses within the piezoelectric disks or bars, the sides of the shell are extended or retracted producing a mechanical movement capable of producing vibrations. The system vibrates at the resonant frequency of the shell, and this type of transducer is of a relatively small size, lightweight and has a high power capability, and has advantages over transducers employing cylinders or mass loaded stacks. Examples of this type of transducer are shown in U.S. Pat. Nos. 3,274,537 and 3,277,433.
However, transducers constructed in accord with the aforedescribed construction are expensive to manufacture, and with many transducers of this type the underwater depth at which operation is possible is limited.